Drill grinding machine

ABSTRACT

A simplified drill grinding machine capable of enabling unskilled persons to be quickly trained for high-production hand sharpening of drills, end mills, and the like, in which the indexing of the drill and the rate and degree of grinding thereof is manually provided and controlled while, at the same time, mechanical positioning and &#39;&#39;&#39;&#39;feel&#39;&#39;&#39;&#39; is provided for carrying out the grinding operation.

United States Patent Hillier [54] DRILL GRINDING MACHINE [72] Inventor:Elmer W. Hillier, Swartz Creek, Mich.

[731 Assignee: Hillier-Thomas Corporation, Swartz Creek, Mich.

[22] Filed: Oct. 19, 1970 [21] Appl. No.: 81,649

[52] U.S.Cl ..5l/96,51/234 [51] Int. Cl. ....B24b 9/00, B24b 47/02 [58]Field of Search ..51/96, 46, 94, 164, 234

[56] References Cited UNITED STATES PATENTS 2,524,279 10/1950 Van Wyk..51/96 [451 Mar. 28, 1972 Hillier ..51/96 Wilson... ..51/96 PrimaryExaminer0thell M. Simpson Attorney-Beaman & Beaman [5 7] ABSTRACT Asimplified drill grinding machine capable of enabling unskilled personsto be quickly trained for high-production hand sharpening of drills, endmills, and the like, in which the indexing of the drill and the rate anddegree of grinding thereof is manually provided and controlled while, atthe same time, mechanical positioning and feel" is provided for carryingout the grinding operation.

8 Claims, 11 Drawing Figures Patented March 28, 1912 3,651,602

3 Sheets-Sheet 1 N v c; N ill-Q K5 s 6 Q Q .Q 1

w E INVENTOR ELMER W. HILLIER BY 2.444104 Ed/x441 ATTORNEYS PatentedMarch 28, 1972 5 Sheets-Sheet 2 ELMER w. HILLIER BY ZM/d rzM/M INVENTORATTORNEYS Patented March 28, 1972 5 Sheets-Sheet 5 INVENTOR ELMER W.HILLIER BY fiMa/I f flrw ATTOR NEYS DRILL GRINDING MACHINE BACKGROUND OFTHE INVENTION Production as well as tool room drills, end mills, and thelike, require frequent and accurate repointing, refacing, splitpointing, web thinning and similar operations performed thereon. Inconnection with the maintenance of high-production machine toolsemploying large numbers of drills, mills, and the like, it is desirablethat sharpening operations be capable of being carried out by unskilledpersons at a rate of several hundred tools per hour per person.

Apparatus for the automatic sharpening of new drills are well known, asis apparatus for repointing drills in which each drill as repointed ismechanically chucked and manipulated with great but time-consumingprecision. The present invention departs from such apparatus andconstitutes an improvement over more simplified forms of grindingmachines as disclosed in U.S. Pat. No. 2,827,741 of which the presentapplicant is a copatentee.

NATURE OF THE PRESENT INVENTION The offhand grinding of a drill is amatter involving good vision, a great deal of experience and aparticular feel" on the part of the operator for the operation beingcarried out. Through the use of steady rests and other accessoriesassociated with tool room grinding wheels, a fair degree of accuracy iscapable of being obtained by hand grinding, provided it is carried outby skilled operators.

In carrying out the present invention the advantages of hand grindinghave been retained, namely, manual holding or chucking, feeding andindexing of the drill. To have accuracy the present invention hasmechanically provided, in a simple and inexpensive manner, positioningand sensing means enabling unskilled operators, after a brief trainingperiod, to repoint 200400 drills per hour.

To a substantial degree, the rate of material removal by a grindingwheel may be determined by observing the sparking of the wheel and byexperiencing the resistance or feel of the grinding wheel against thetool being sharpened. Also, when dull, broken and nicked drills arebeing sharpened, it is desirable to inspect the drill during thegrinding operation to avoid unnecessary removal of material. In carryingout the essence of the present invention both visual and audibleindications of the grinding operation, together with the feel" orresistance thereof are coordinated in combination with the operator withsimple mechanical aids which enable the unskilled persons to, in effect,hand sharpen reusable tools rapidly and accurately.

One of the aids mentioned above takes the form of a stop finger for thetool to be ground which is capable of a slight movement toward thegrinding wheel effected by manual pressure exerted on the shank of thetool in excess of that pressure required to carry out the final portionof the grinding cycle. In this manner, the rate of grinding is manuallycontrolled in the presence of an operational feel built into theapparatus in the form of an adjustable reaction which may take the formof spring pressure. This feel" reacting against the operator through theshank of the tool assures equal lip height being obtained at theconclusion of the sharpening operation.

Another of the aforesaid aids takes the form of an improved holder andstop in which the drill, or the like, is manually held by one hand whilebeing swung through an arcuate path by the other hand to cause the endof the drill being ground to have a sweep through" engagement with thegrinding wheel.

A further aid to high production drill grinding is provided through theprovision of a simple setup procedure coupled with convenientwheel-dressing means, the wheel being so dressed that grinding may takeplace axially along the peripheral portion of the grinding wheel withoutresetup by moving the drill holder along a path parallel to the axis ofrotation of the wheel.

BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects andadvantages of the invention will be apparent from the followingdescription and accompanying drawings wherein:

FIG. 1 is a perspective view of the grinding machine embodying thepresent invention, the wheel dresser being omitted from the showing forclarity,

FIG. 2 is a fragmentary elevation of FIG. 1 taken from the left endthereof,

FIG. 3 is a fragmentary elevational view of a detail of FIG. 1 partlyshown in vertical cross section and partly disassembled,

FIG. 4 is a cross-sectional view taken on line IV-IV of FIG. 1

FIG. 5 is a cross-sectional view taken on line V-V of FIG. 3,

FIGS. 6 and 7 are views taken at to each other of the drill holder andstop finger assembly shown removed from the grinding machine,

FIG. 8 is a side elevational view of theeccentric coupling for the drillholder shown disassembled from its associated structure,

FIG. 9 is a cross-sectional view taken on line IX-IX of FIG. 1

FIG. 10 is a view of the wheel dresser, and FIG. 11 is a diagrammaticview of the association between the working end of the drill, the stopfinger and the grinding wheel.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, inFig. l the invention is illustrated in the form of a bench top toolgrinding machine 10 having a rigid rectangular base 12 upon which isrigidly mounted a' toolroom type grinder l4 and a rotary table 16.Preferably, ways for the lower carriage 18 of the table 16 are disposedwith their longitudinal axes parallel to the axis of rotation of thegrinding wheel 20. Thus, when the wheel 20 is dressed by the wheeldresser 22 to provide the wheel 20 with a substantially cylindricalouter peripheral surface for tool grinding thereon, any surface carriedon the turret 24 of the upper carriage 26 will move along the axis ofrotation of the wheel 20 when the lower carriage I8 is moved by rotationof the handle 28 attached to a lead screw, in a well known manner.Likewise, through rotation of the handle 30, the upper carriage 26 ismoved normal to the axis of rotation of the wheel 20.

For reasons which will hereinafter appear, the mounting plate 32 isshown substantially parallel with the front edge 34 of the rectangularbase 12. When so arranged the turret 24 is rotated through an angle inthe order of l ll 5 to the longitudinal axis of the ways for the uppercarriage 26 and the longitudinal axis for the ways for the lowercarriage 18 are disposed at an angle in the order of l1l5 to the frontedge 34 of the base 12.

Mounting plate 32 is shown rigidly attached to the turret 24 throughT-bolts 36 disposed in the T-slots 38 clamping the L- bracket 40. Bolts42 removably attach the plate 32 to the L- bracket 40.

Bearing structure for the rock shaft carrying the tool holder 44 takesthe form in the illustrated embodiment of a tube 46 having counterbores48 and 50 at opposite ends. Rock shaft 52 has a close fit at oppositeends with the identical ball bearing structures 54. However, thecounterbore 50 is of slightly elongated shape when compared with thecounterbore 48 with the result that a small amount of clearance existsin one direction between the outer bearing race 56 and the counterbore50.

As shown in Fig. 5, the tube 46 is rigidly attached to the plate 32 bywelding. A boss 58, extending from one face of the plate 32, has a hole60 machined therein which hole extends through the plate 32 as well asthe wall of the counterbore 50, the longitudinal axis of the hole 60coinciding with the elongated axis of the counterbore 50 which providesthe clearance with the outer bearing race 56 above described. Set screw62 holds a threaded bushing 64 in the hole 60. A compression spring isdisposed between the bushing 64 and the outer bearing race 56 tocontinuously urge the outer race 56 toward the abutment 68 provided bythat portion of the counterbore 50 opposite the hole 60. To rigidlyclamp the outer bearing race 56 within the counterbore 50, when desired,a clamping screw 70, having a knurled head, is threaded in the bushing64 and may be projected by rotation through the center opening of thespring 66 into engagement with the outer bearing race 56. Adjustment ofthe pressure exerted by the spring 66 may be made by regulating theposition of the bushing 64 within the hole 60 through manipulation ofthe set screw 62.

Rock shaft 52 is embraced by torsion spring 72 having one end 74extended through a cross hole 76 and the opposite end 78 anchored inhole 80 of the tube 46.

As shown in Figs. 1 and 3, a rock lever 82 for oscillating the toolbeing ground relative to the grinding wheel 20, has its end 84 fixed inthe collar 86 adjustably attached to the left end 88 of the shaft 52 bythe clamping screw 90. Attached to the same end of the shaft 52 is anadjustable stop screw 92 threaded in the arm portion 94 of the collar96. A set screw 98 is provided to hold the collar 96 in differentpositions of adjustment on the shaft 52.

A coupling 100 is attached to the end 102 of the rock shaft 52 by setscrew 104. An eccentric stub shaft 106 on the outer end of the coupling100 is received in the bore 108 of the boss 110 on the L-bracket 112 ofthe tool holder structure. A set screw 114 rigidly holds the L-bracket112 in different positions of angular adjustment on the shaft 106.

Swivel block 116 has a threaded boss 118 which projects from the upperside thereof through a hole 120 in the L- bracket 112. A friction nut122 in combination with a friction washer 124 functions to frictionallyhold the block 116 in different positions of adjustment, the resistanceto movement of the block 116 relative to the L-bracket 120 beingregulated by the tightening of the nut 122. Bore 126 is provided inblock 116 to receive different size drill bushings. By providing athreaded hole 128 in the boss 118 extending into the bore 126, drillbushings may be conveniently held and removed through manipulation ofthe set screw 130.

Stop finger 132 of the tool holder structure comprises a block portion134 from which projects a rigid stem 136 received in the bore 138 of theblock 116 and held in different positions of adjustment by the set screw140 disposed in a threaded cross hole 142. As more clearly shown in Fig.9, the stop finger 132 has an L-shaped abutment and index portion 144 onthe outer end of a threaded shank 146. To provide the portion 140 withmicrometer adjustment, the shank 148 is threaded into a knurled handle150 which is provided with a flange 152 disposed in cross slots 154which permit the handle 150 to be rotated yet confined against axialmovement relative to the block portion 134. The portion 144 is slidableback and forth in a complementary bore 156 in the block portion 134through rotation of the handle 150.

SETUP FOR GRINDING DRILLS In practice it will be understood that it iscontemplated that the operator will sit or stand before the edge 34 ofthe base 12 of the machine with the tool holder structure being locatedat a height at which the operator may comfortably insert and index thedrill to be sharpened, the location of the axis of rotation of the wheelbeing disposed at an angle to the edge 34 in the order of l l-l5contributing to such comfort, particularly when the machine is beingused to split drill points.

To setup or place the machine on center" for the purpose of rapidlyrepointing a large number of similar size drills, for example, thefollowing steps are taken with the rock shaft 52 in its at rest positionunder the stress of the torsion spring 72 and the outer bearing race 56being held against the abutment 68 defined by a portion of thecounterbore 50 by either the spring 66 or the clamping screw 70:

a. Coupling 100 is adjusted on the end 102 of the rock shaft 52 byloosening and then tightening the set screw 104 to substantially disposethe eccentric stub shaft 106 with its longitudinal axis in a horizontalplane through the common longitudinal axis of the coupling and the rockshaft 52 and on the side of said common axis remote from the wheel 20,the axis of rotation of which is slightly disposed above this sameplane. When the shaft 106 is so located, the flutes of the drill will beground at the tip of the drill as arcuate surfaces by passing the toolthrough the wheel as distinguished from plunge grinding, the latterbeing of a nature which would provide the flutes with a substantiallyflat ground surface. Should such a ground surface be desired it may besubstantially obtained by the illustrated machine by adjusting thecoupling 100 on the rock shaft 52 to dispose the shaft 106 at 90 to theposition described above for arcuate grinding.

b. With the shaft 106 located in the horizontal plane defined in (a) theL-bracket 112 is adjusted on the shaft 106 by loosening and tighteningthe set screw 114 to dispose the longitudinal axis of the threaded boss1 18 in a substantially vertical position.

c. With the wheel 20 dressed to present a substantially cylindricalperipheral grinding surface, the block 116 is manually moved about theaxis of the threaded boss 118 to dispose the longitudinal axis of thebore 126 at the necessary angle to the grinding surface of the wheel 20to provide drills with points of the desired angle, the block 116 beingfrictionally held in the selected position.

d. The selected bushing having a bore substantially corresponding to thesize of the drill to be repointed is then inserted into the bore 126 andthe set screw tightened to hold the bushing in place. With the drillbushing in place, the stop finger 132 can then be adjusted to the drillsize being repointed by using one of such drills for the setup andmanipulating the handle to place the L-shaped outer end 144 in aposition to function as both a stop and as a rest for a flute at one endof the drill while exposing another flute of the drill to the grindingoperation.

e. With the setup drill lightly held by hand by the shank and with thepoint of the drill resting on the end 144 of the stop finger 132, theoperator applies a slight axial pressure on the shank as well as a lighttorsional pressure clockwise to hold the drill against the end 144 in anindex position determined by the engagement of one of the cutting edgesof the drill with a surface of the end 144. With the drill thus manuallypositioned and held by the operators right hand, the handles 28 and 30,on the rotary table 16, are manipulated to so position the stop finger132 with respect to the wheel 20, that when the rock shaft 52 isoscillated by the rock shaft lever 82, the exposed flute of the drill onthe end 144 will lightly brush the grinding surface of the wheel 20. Themachine is now on center" and setup for high-production hand grinding ofdrills.

With the tool holder on center," as described above, and the clampingscrew 70 backed off so that modest manual axial pressure on the toolshank will cause the outer bearing race 56 to be displaced feel" theabutment portion 68 of the elongated counterbore 50, oscillation of therock shaft 52 by the left hand of the operator through the rock lever 82will result in a substantial removal of material from the drill fluteengaging the end 144 and exposed to the grinding wheel 20. Preferably,upon the completion of each oscillation of the rock shaft 52, theoperator will index the drill clockwise to successively grind the flutesof the drill to be repointed, the amount of axial pressure on the shankdetermining the amount of material removed and the amount of materialbeing removed during each oscillation being proportional to the distancethe outer bearing race 56 is removed from the abutment portion 68against the tension of the spring 66.

In practice, the elongation of the bore 50 exceeds the diameter of theouter bearing race 56 on the order of 0.030 inches. As may be readilyunderstood, the tension of the spring 66 provides the feel experiencedby the operator during the grinding operation, with the shank of thedrill being held in his hand and a modest amount of pressure beingapplied axially to the shank.

In order to grind the flutes of the drill with equal height at thepoint, it is not necessary that the operator uniformly remove materialeach time the drill is oscillated and indexed on the end 144 of the stopfinger 132. When the operator observes that all nicks and other defectshave been removed from the ground flutes of the drill, he need only,thereafter, reduce the axial pressure on the drill shank to enable thespring 66 to bring the tool holder structure and drill point supportedthereon back to the on center position by continuously indexing andoscillating the drill to permit the drill to spark out on the grindingwheel 20. This on center" grinding position during which any excessmaterial on one flute, as compared with another, will equalize theheight of the ground flutes and center the drill point with greataccuracy notwithstanding the hand holding and indexing of the drill.

It should be appreciated that the length of the drill being ground doesnot complicate either the setup described above or the high productiongrinding of a batch of drills of varying overall length.

To regulate the amount of clearance or relief of the cutting edge of thedrill, the boss 110 may be slightly rotated on the stub shaft 106.Rotation in one direction increases the clearance and in the oppositedirection reduces the clearance, even to the point of negativeclearance, if desired.

One of the inherent features of the illustrated tool holder resides inthe fact that rotation of the block 116 in a direction to increase thepoint angle also increases the cutting edge clearance without any otheradjustment being made.

In order to alter the chisel edge angle of the drills being repointed,it is only necessary to slightly raise or lower the end 144 of the stopfinger 132 by loosening the set screw 140 to enable the end 144 to berotated about the longitudinal axis of the stem 136. This enables theindexed position of the drill on the end 144 to be slightly altered.

DRILL SPLITTING Resetting the machine from drill grinding, describedabove, to drill splitting is facilitated by having the grinding wheel 20provided with a splitting section indicated at 20 disposed at one radialface thereof. Section 20' is of a composition capable of being dressedto a sharp comer and retaining the same without dressing for thesplitting of many drills. The resetting steps follow:

a. The clamping screw 70 is run in to project its end into contact withthe outer bearing race 56 to rigidly hold the same in contact with theabutment portion 68 of the elongated bore 50.

b. Set screw 114 is loosened to permit the boss 110 to be rotated on theshaft 106 from the position used in drill grinding to a position removedtherefrom in the order of 45 in a direction to raise the end 144.

c. With the setup drill resting in an index position on the end 144, theend 144 is lowered by rotating the same about the stem 136 until theindexed position disposes the chisel edge of the drill substantiallynormal to the axis of the rock shaft 52.

d. With the drill on the end 144 and positioned in front of the outeredge of the wheel section 20, the drill may now be fed into the wheelsection 20' through manipulation of the carriages of the rotary tablenecessary to obtain the desired degree of point splitting, the positionof adjustment of the pointed end of the drill being ultimately under thecontrol of the stop 92. The setup for splitting is now complete and thedrill ends to be split are supported and indexed on the end 144 of thefinger stop 132.

I claim:

1. A grinding machine for the hand grinding of tools such as drillscomprising a grinding element, a holder in which a tool is manuallysupported, said holder including a stop against which a portion of theworking end of the tool abuts to resist pressure manually exerted on theshank of the tool, support structure for said holder for substantiallydefining the manually effected path of movement of said stop relative tosaid grinding element to present another portion of the working end ofthe tool to said element, and yieldable means associated with said stopand subjected to manual axial pressure exerted on the tool shank forslightly modifying the path of movement of said stop relative to saidgrinding element.

2. A machine as defined in claim 1 wherein said support structureincludes a rock shaft about the longitudinal axis of which said holderis manually oscillated to bring the tool into engagement with thegrinding element.

3. A machine as defined in claim 2 wherein rigid structure is providedfor the relative positioning of said grinding element and said rockshaft, said yieldable means being disposed between said rock shaft andsaid rigid structure.

4. A machine as defined in claim 3, there being means on said rigidstructure for rendering said yieldable means inoperative.

5. A machine as defined in claim 4, wherein said rigid structureincludes adjustable means for moving said holder relative to saidgrinding element and along the path parallel to the axis of rotation ofsaid element.

6. A grinding machine as defined in claim 1 wherein said yieldable meansincludes a spring element, a rigid abutment associated with said supportstructure, said spring element engaging said support structure andcontinuously acting to urge said support structure against saidabutment.

7. A machine as defined in claim 1 wherein means are provided foradjusting the degree of yieldability of said yieldable means.

8. A machine as defined in claim 1 wherein there are means forsupporting said holder for movement about one axis for oscillating saidstop relative to said grinding wheel to grind the lips of the tool witharcuate surfaces, and means for supporting said holder for swiveladjustment about an axis disposed normal to said first axis to changethe point angle.

1. A grinding machine for the hand grinding of tools such as drillscomprising a grinding element, a holder in which a tool is manuallysupported, said holder including a stop against which a portion of theworking end of the tool abuts to resist pressure manually exerted on theshank of the tool, support structure for said holder for substantiallydefining the manually effected path of movement of said stop relative tosaid grinding element to present another portion of the working end ofthe tool to said element, and yieldable means associated with said stopand subjected to manual axial pressure exerted on the tool shank forslightly modifying the path of movement of said stop relative to saidgrinding element.
 2. A machine as defined in claim 1 wherein saidsupport structure includes a rock shaft about the longitudinal axis ofwhich said holder is manually oscillated to bring the tool intoengagement with the grinding element.
 3. A machine as defined in claim 2wherein rigid structure is provided for the relative positioning of saidgrinding element and said rock shaft, said yieldable means beingdisposed between said rock shaft and said rigid structure.
 4. A machineas defined in claim 3, there being means on said rigid structure forrendering said yieldable means inoperative.
 5. A machine as defined inclaim 4, wherein said rigid structure includes adjustable means formoving said holder relative to said grinding element and along the pathparallel to the axis of rotation of said element.
 6. A grinding machineas defined in claim 1 wherein said yieldable means includes a springelement, a rigid abutment associated with said support structure, saidspring element engaging said support structure and continuously actingto urge said support structure against said abutment.
 7. A machine asdefined in claim 1 wherein means are provided for adjusting the degreeof yieldability of said yieldable means.
 8. A machine as defined inclaim 1 wherein there are means for supporting said holder for movementabout one axis for oscillating said stop relative to said grinding wheelto grind the lips of the tool with arcuate surfaces, and means forsupporting said holder for swivel adjustment about an axis disposednormal to said first axis to change the point angle.